Outspoken billionaire investor Mark Cuban told CNBC on Wednesday that he would "absolutely not invest in IBM".

"IBM is no longer a tech company," Cuban told CNBC. "They have no vision. What they've evolved into is a company that does [arbitrage] on acquisitions. It's stock buybacks. Who is IBM anymore?"

In the past, when you thought of computers or software services, you thought of "Big Blue," Cuban said.

"But today, they specialize in financial engineering. They're no longer a tech company, they are an amalgamation of different companies that they are trying to arb[itrage] on Wall Street, and I'm not a fan of that at all," he says.

That's not entirely fair. IBM's "financial engineering" was an attempt to deliver on a promise to achieve $20 earnings per share by 2015, a promise that was made by CEO Ginni Rometty's predecessor Sam Palmisano. If Rometty had succeeded in doing that, even during this period of declining revenue, she might have been hailed a genius.

But she didn't. And on Monday, she told investors IBM was abandoning that promise.

And now, Rometty is left with no clear, articulated turnaround strategy.

IBM's revenues are declining because there's a big shift going on in the way companies are buying tech. Instead of buying their own software and hardware for their own data centers, then hiring expensive consultants to stitch it all together, they are renting that technology, which is often hosted elsewhere. That's called "cloud computing."

All the big tech firms are shifting from the old way of selling stuff to this new way with varying degrees of success: SAP, Oracle, Microsoft, Dell, HP and IBM are all getting into the cloud.

IBM actually has game in all the new growth areas: This includes cloud computing, big data/analytics, and mobile computing.

IBM under Rometty, meanwhile, has been able to accomplish the following:

But Rometty needs to make it clear that it will take time to shift IBM into growth mode again. And whatever she promises next time around, she needs to deliver.

IBM sent CNBC this statement in response to Cuban: "IBM will accelerate our growth strategy, creating a dedicated cloud business and specialized units to serve industries and professions being transformed by data and analytics. IBM will also continue to return money to shareholders, in addition to maintaining our commitment to R&D and to invest in our business. It is all part of our commitment to delivering higher value to our clients."